Lownsdale Square, Chapman Park, and Terry Schrunk Plaza have been centerpieces of many demos and actions. They are a series of 3 parks, called the Plaza Blocks, each occupying a city block.
Terry Schrunk Plaza is Federal property. Groups who gather there are pre-dominantly from the right wing, however there has been a few liberal demos.
Northwest-ish is Chapman Square Park. This is not Federal property, and as of Mid-July there has been no benches or seating areas. Across the street from Chapman is the Justice Center [link coming soon]. If you are at Chapman and facing the Justice Center you are facing East.
And to the Northwest-ish of Chapman is Lownsdale Square. In the middle of Lownsdale Square stands a sculpture in memory of the Oregonians killed in the Spanish-American War. On the West side of Lownsdale, facing the Multnomah County Courthouse [link coming soon], is a Fountain for Company H, a memorial to US Soldiers who invaded the Philippines. To the East there is the U.S. District Court for the District of Oregon, it is a federal courthouse.
One block North of Lownsdale Square is a 7-11 that has in the past been very accommodating to protestors.